Vacuum distillation



5, 1959 l M. ADDlLL 2,901,425

VACUUM DISTILLATION Filed Deg. 28. 1953 9 Sheets-Sheet 1 MOVED 30083GHddOJ.

INVENTOR.

P. M WADDILL /WW M ATTORNEYS OIL RESIDIUM FIG.

' Aug. 25, 1959 P. M. WADDILL VACUUM DISTILLATION Filed Dec. 28, 1953 9Sheets-Sheet 2 N at INVENTOR. P. M WADDILL ATTORNEYS P. M. WADDILLVACUUM DISTILLATION' Aug. 25, 1959 Filed Dec. 28, i953 9 Sheets-$heet 3I22 INVENTOR.

P.M.WADDILL.

FIG. .5.

ATTORNEYS Aug. 25, 1959 P. M. WADDILL 2,901,425

VACUUM DISTILLATION Filed Dec. 28, 1953 9 Sheets-Sheet 4 INVENTOR. P. M.WADDILL SMWM ATTo/ ygrs Aug. 25, 1959 P. M. WADDILL VACUUM DISTILLATION9 Sheets-Sheet 6 Filed Dec. 28, 1953 Aug. 25, 1959 P. M. WADDlLL VACUUMDISTILLATION Filed Dec. 28. 1953 9 Sheets-Sheet 7 ut R INVENTOR. P MWADDILL.

ATTORNE S United States Patent VACUUM DISTILLATION Paul M. Waddill,Bartlesville, Okla, assignor to Phillips Petroleum Company, acorporation of Delaware Application December 28, 1953, Serial No.400,450

3'1 (llaims. (Cl. 208-652) This invention relates to process andapparatus for the distillation of distillable materials. In one aspectthis invention relates to the vacuum distillation of oils. In one aspectthis invention relates to the distillation of hydrocarbon oils. Inanother aspect this invention relates to the vacuum reduction of heavyhydrocarbon oils to produce clean low carbon residue distillates inhigher yields and residual high softening point pitch in lower yieldsthan have been obtained heretofore. In another aspect this inventionrelates to process and apparatus wherein a hydrocarbon oil is vacuumdistilled in a first stage to produce a first residual pitchdistillation product and wherein the said residual product is thenredistilled in a second vacuum distillation stage to produce a stillhigher softening point pitch. In another aspect this invention relatesto process and apparatus wherein a first residual pitch distillationproduct is redistilled in the same distillation system to produce astill higher softening point pitch together with additional distillatefractions, Without the need for heat or applied vacuum not alreadyutilized in producing the initial residual pitch product. In anotheraspect this invention relates to the utilization of lower temperaturesfor effecting the vacuum distillation of residual oils than have beenutilized heretofore. In another aspect this invention relates to acombination of process steps wherein a heavy hydrocarbon oil is vacuumreduced in a first stage and then further reduced in a econd stage, andwherein residual product of the second stage reduction is subjected to aseries of steps comprising visbreaking, cracking of resulting visbrokenresiduum, and vacuum reduction of resulting cracking residuum, toprovide a final residual high melting pitch, and for conversion of gasoil distillate recovered from the second stage residuum, to lighterproduct. in still another aspect this invention relates to thedistillation of distillable materials under conditions providing for lowpressure drop across the distillation zone under high vacuum, and isadvantageously applied to the vacuum reduction of residual hydrocarbonoils to provide lower yields of higher softening point residual pitchtogether with concomitantly higher yields of distillate. In anotheraspect this inven tion relates to a vacuum distillation process in whicha distillable material is partially flash vaporized and particlesentrained in resulting vapors are settled from the vapors in whole or inpart as desired, prior to condensing the vapor in one or more condensingsteps, at least one of which is eflected in heat exchange relation ofthe vapors with a relatively cool liquid spray. In another aspect thisinvention relates to a vacuum distillation process wherein a hydrocarbonoil is partially flash vaporized, and resulting vapors are maintained ata residence time sufficient to permit settling therefrom of at least aportion of entrained particles, prior to effecting condensation of thevapors in heat exchange relation with cooler liquid spray, the latteremitted in concurrent flow relation withthe said vapors so as to achievea lowered pressure drop across the vacuum distillation chamber. Inanother aspect this invention relates to apparatus comprisinga flat ringdisand the like.

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posed peripherally about the inner wall of a chamber section in asubstantially horizontal distillation chamber, for preventing flow ofunvaporized liquid in an axial directionalong the chamber side wallsfrom the partial flashing section to a downstream section in thedistillation chamber. In another aspect this invention relates to theintro duction of feed into a flash vaporization section of a vacuumdistillation chamber, in an upstream direction, from an open-end pipe,preferably against a coalescing surface such as provided by a wire rnat,so as to facilitate separation of unvaporized feed from vapors formed.In another aspect this invention relates to the vacuum distillation of ahydrocarbon oil in a single stage by partially fiash vaporizing the oil,contacting the resulting vapors with a liquid spray under temperatureconditions effecting partial, or substantially no condensation of thevapors, as desired, and removal of entrainment therefrom, and theneffecting substantially complete condensation of resulting vapors inheat exchange relation vith a relatively cool liquid spray, emittedagainst the direction of flow of vapors contacted therewith.

This application is a continuation-in-part of my copending applicationSerial No. 241,183, filed August 10, 1951, now abandoned.

Heretofore in the vacuum distillation of residual oils, distillatefractions having high carbon residues have been obtained, together withresidual pitch or tar fractions in high yield, as for example from 507()volume percent of residue based on the total oil charged. Furthermorethe distillate fractions so produced are dirty, that is, they are highcarbon residue oils containing heavy carbonaceous materials present as aresult of the entrainment of such materials in the vapors during thevacuum distillation. Such high carbon residue gas oils are undesirableas feed stock for various conversion processes. Furthermore whenemploying conventional oil reduction operations some of the gas oilcomponents of the oil charge are lost to the distillation residue at theexpense of gas oil yield.

My invention is concerned with the vacuum reduction of hydrocarbon oilsparticularly crude residua, for the recovery of clean gas oil fractionsand for the concomitant recovery of residual pitch. My invention isadvantageously applied to the further reduction of an initial residualpitch distillation product to provide a still higher softening pointpitch and additional gas oil distillate product, and when desired,without the need for applying any heat or vacuum in addition to thatalready utilized in carrying out the initial distillation. My inventionis further concerned with a method for the vacuum distillation ofhydrocarbon oils so as to operate the distillation at any givenpressure, at a lower temperature than utilized heretofore.

An object of my invention is to provide apparatus and process for thedistillation of distillable materials. Another object of my invention isto provide for the distillation of a distill-able material, underconditions providing for low-pressure drop across the distillation zoneunder high vacuum. Another object of my invention is to provide for thevacuum distillation of oils. Another object is to provide for the vacuumreduction of residual hydrocarbon oils. Another object is to provide forthe recovery of residual pitch from oil residua in lower yield, andhaving a higher softening point than has been obtained heretofore bydistillation alone. Another object is to provide for the recovery ofclean gas oil fractionsfrom crude oil residua in yields higher than havebeen obtained heretofore. Another object is to provide pitch of improvedquality for use in coke production, container manufacture, as asurfacing agent, road coating,

Another object is to provide for the recovery of valuable hydrocarbonsfrom crude oil residua.

Still another object is to provide for the vacuum distillation of ahydrocarbon oil at any given pressure level, at a temperature lower thanthat utilized heretofore. Still another object is to provide a processfor vacuum distilling a residual hydrocarbon oil to produce an initialresidual pitch of high softening point, and then for further reducingthe initial pitch product in a second reduction stage. Still anotherobject is to provide a process for vacuum distilling a residualhydrocarbon oil to produce an initial pitch residue of high softeningpoint, and then to further reducing the initial pitch product in thesame distillation system to produce a pitch residue of still highersoftening point, without the need for heating or vacuum-producing meansother than those employed in carrying out the initial distillation.Still another object is to provide a combination process wherein ahydrocarbon oil is vacuum reduced in two successive stages and resultingresiduum product is subjected to visbreaking followed by cracking ofresulting visbroken residuum and vacuum reduction of the resultingcracked residuum.

In accordance with this invention, apparatus and process are providedwherein a distillable material is partially vaporized and at least aportion of entrained particles are removed from resulting vapors, bysettling same from the vapors by gravity alone, or, by contacting thevapors with a liquid spray, prior to condensing resulting vapors in oneor more condensation steps, at least one of which condensation iseffected by contacting the vapors in heat exchange relation with arelatively cool liquid spray; in accordance with one concept, myinvention providing for introducing a distillable material into a firstsection of a distillation zone under flashing conditions so as tovaporize a portion of the said material, thus forming vapors containingentrained liquid particles, passing vapors from the said first sectioninto a second and downstream section of said distillation zone andtherein separating from the said vapors at least a portion of saidparticles entrained therein, passing vapors from said second sectioninto a third section of said distillation zone in heat exchange flowrelation therein with a spray of liquid droplets maintained at atemperature below that of the vapors contacted therewith so as tocondense same, and recovering liquid product from the said distillationzone; in accordance with another concept, my invention providing anelongated chamber, preferably disposed substantially horizontally, aconduit extending into said chamber, a spray nozzle assembly in saidchamber, a baflle product to the flashing step together with fresh feedto section transversely closing said chamber and adapted to deflectliquid droplets from vapors passed therethrough and disposedintermediate said spray nozzle assembly and the end of the said firstconduit, and conduit means for withdrawing liquid and any uncondensedvapor from the said chamber; another concept providing means forarresting downstream flow in an axial direction of unvaporized portionsof liquid along the inner periphery of a substantially horizontallydisposed distillation zone, comprising a flat ring disposed around theinner periphery of the said zone disposed downstream from its feedinlet. In accordance with narrower concepts of my invention, the saidseparation of entrained particles from vapors can be effected by (1)passing the vapors in contact with a flow of atomized droplets as aspray, the latter spray being oriented to impinge on the entrainedparticles in such a manner that removal of entrainment occurs, such aspassing the vapors against a flow of atomized droplets maintained at atemperature at least as high and under a momentum at least as great asthat of entrained particles contacted therewith, whereby impingingdroplets and impinged particles settle to provide entrainment-freevapors; (2) contacting the vapors with a spray of atomized droplets soas to condense a portion of the vapors and, concomitantly removeentrained particles with condensate from the vapors-the direction offlow of atomized droplets, contacted with vapors, being countercurrentto, concurrent with, or transverse to the direction provide asubstantial proportion of requisite sensible heat in the flashingsection and to reduce requisite peak feed preheat temperatures; furtherreduction of initial residuum product, in one or more successive stages;further reduction of initial residuum product in a second stage, in thesame distillation system, without the need for supplemental heat and/orvacuum; and subjecting residuum distillation product to a series ofsteps comprising visbreaking, recycle cracking and vacuum reduction toprovide a final high softening point residual pitch product, togetherwith gasoline as product.

In accordance with one embodiment of my invention, illustrated withreference to the drawings as discussed hereinafter, a distillablematerial such as a hydrocarbon oil residuum, generally a topped crude ora residuum from a topped crude cracking operation is heated to atemperature at which very little cracking takes place, or moredesirably, none at all, such as within the limits of 600-900 F. Theheated liquid is discharged into a flash, or first section, of adistillation zone, which distillation zone is maintained undersubatmospheric pressure, generally at an overall absolute pressure fromabout 0.1 to 21 mm. Hg, and often from 0.1 to 8 mm. The heated chargeupon being introduced into the first section is flashed, with thehighest boiling components of the charge material remaining unvaporized.These unvaporized materials comprise residual pitch, a major proportionof which settles as liquid in the first section. As is inherent in allflash vaporization operations, particularly with heavy oils, a smallportion of the unvaporized material is entrained in the flashed vaporsas small finely divided liquid droplets, often appearing as a fog ormist. Such an entrainment of finely divided liquid droplets is typicalof that also occurring in conventional vacuum distillation procedures.In conventional processes, the entrained liquid is carried on throughthe distillation system and is recovered in the gas oil fractions,thereby contributing to the high carbon residues so typical of thoserecovered gas oil fractions. As described hereafter, my inventionprovides for arresting these finely divided suspended materials, and fortheir separate recovery from the recovered gas oil distillates. Theseentrained fog-like materials must be removed from the vapor containingthem in order that clean distillate fractions, i.e., of low carbonresidue, be recovered. This is done by passing the vapors from the flashsection, i.e., the first section, into a second section of thedistillation zone downstream and adjacent the first section, against anatomized oil spray, which completely blankets the path of vapor flow,maintained at substantially the Same temperature or more preferablyslightly above that of the vapors contacted therewith. The atomizedliquid oil droplets are ejected from the spray nozzles under conditionsaffording each of them at least as great and preferably a greatermomentum than that of each of the liquid particles also referred toherein as droplets, entrained in the vapor. In this manner the sprayeddroplets impinge against the entrained droplets, and cause the impingeddroplets to settle with the impinging or sprayed droplets to the bottomof the second section. It is to be understood, however, that in thepractice of this embodiment, the momentum of the sprayed inaterial neednot be equal to that of the'entrained materials, as long as settling ofimpinged and impinging materials is eifected prior to condensing thesaidvapors, and also, that the spray may be emitted in any predetermineddirection as desired, i.e., transverse to vapor flow, concurrenttherewith, or countercurrent thereto. Also, if desired, spraytemperature may be below that of vapors contacted therewith, so thatsome condensation will take place and condensate thus provided cansettle from the vapors with entrainment.

Vapors, having been contacted with the spray droplets under theconditions described, are free of entrained liquid and are passed fromthe second section into a third section of the distillation zonedownstream from the second section and adjacent to it, against arelatively cool vsecond oil spray, maintained at a temperature lowerthan that of the vapors contacted therewith, so as to condense at leasta portion of those vapors as for example a temperature of from 3 to 500F. below that of the contacted vapors. Condensate thus formed settles inthe bottom of the third section. Settled condensate is recovered fromthe third section as clean distillation product. Similarly, the processis continued in as many additional downstream sections as desired, andany uncondensed portions of original charge are removed from the finalsection of the distillation zone as vapors.

The settled liquid, i.e., the pitch residue, in the first section isthen withdrawn and is introduced at its existing temperature, i.e., withor without supplemental heating, into communication with a section ofthe distillation zone downstream from the first section, either intosuch a section or into a vacuum flash vessel directly in communicationwith such a downstream section. In either case the withdrawn residualliquid is further flash vaporized by virtue of the fact that theupstream or first section of the distillation Zone operates inherentlyat a higher pressure than any downstream section therein, because of thepresence in the first section of a larger proportion of the total vaporsin the distillation zone, and accordingly, a pressure drop is developedacross the entire distillation zone which is generally within the limitsof from about 2-15 mm. Hg absolute, sometime being as high as 15-20 mm.Hg absolute, dependent upon the specific operation.

I prefer to carry out this embodiment of my process by introducing thewithdrawn residual liquid into a section of the distillation zonedownstream from the initial flash section. However, the residual pitchcan be passed from the first or flash section directly to a seconddistillation zone generally a flash vaporization vessel maintained indirect communication with a downstream portion of the initialdistillation zone. As in the preceding described embodiment, thepressure in the second distillation zone is inherently lower than thatin the first or flash section of the initial distillation zone.

In the copending application Serial No. 188,604, to V. C. Cavin, W. H.Acker, and P. M. Waddill, filed October 5, 1950, now abandoned, and inthe co-pending application Serial No. 343,560, filed March 20, 1953, nowU.S. Patent No. 2,805,981, as a continuation-in-part of the said SerialNo. 188,604, of which I am one of the inventors, a vacuum distillationprocess is disclosed in which the initial oil charge is. partially flashvaporized and vapors are freed of entrained droplets in a secondsection, and then partially or completely condensed in one or more of aseries of downstream zones in a manner similar to that already describedabove. In the process of each of these applications referred to, i.e.,Serial Numbers 188,604 and 343,560, pitch residue is recovered from thefirst or second section as product, or can be further heated and thenvacuum distilled in a separate vacuum distillation zone at a lowerpressure by means of supplemental heating and vacuum producing means,separate and apart from that employed in the first distillation zone, toprovide a final reduced pitch product of high softening point. As statedabove, I have by one concept of this 6 invention taken advantage of theinherent pressure drop across the vacuum distillation zone so as tofurther flash distill the initial residual pitch residue in the samedistillation system without the'need for heating or applied vacuum,other than that utilized in the initial flash distillation step.

I have provided further for conducting the flash vaporization, both inthe initial flash vaporization step and in the succeeding flashvaporization step, at a temperature lower than that utilized heretoforewhile maintaining the pressure substantially unchanged by dispersing thefeed in a finely divided state so as to charge liquid feed particleshaving extremely small radii of curvature. When operating in this mannerflash vaporization is facilitated at a lower temperature and vaporshaving a density many times greater than otherwise formed are obtained,the latter resulting in decreased vapor velocities. The concomitantlower distillation temperatures eliminate the necessity for superheatingthe feed to attain the requisite vaporization.

For a further clarification of my invention, reference is made to theattached diagrammatic drawings. Figures 1 and 2 are diagramm'aticflowsheets illustrating various concepts of process and apparatus employedin the practice of my invention. Figure 3 shows an elevationof a bafflesection that can be employed in the vacuum chamber illustrated in eachof Figures 1 and 2, taken along the line 3-3 of Figure 1. Figure 4 is aside elevation of the baffle structure of Figure 3 taken along the line4-4 of Figure 3. Figure 5 is a plan View of the baffle structure ofFigure 3, taken along the line 55 of Figure 3. Figure =6 is a crosssectional view of a preferred arrangement of sprays, employed in theapparatus of Figures 1 and 2, and is taken along the line 6--6 ofFigure 1. Figure 7 is a cross sectional view of an alternative form ofsection III in the apparatus of Figure 1. Figure 8 is illustrative of abaffle section employed in section III of the apparatus of Figure 1,alternative to the guard assembly comprising vessel 79, to prevent flowof any entrained liquid droplets into the vacuum producing system 28.Figure 9 is a plan view of the battle section of Figure 8 taken alongthe line 99 of Figure 8. Figure 10 is a cross sectional view of abellowstype expansion joint for use in .the hot oil lines of theapparatus of Figures 1 and 2. Figure 11 is illustrative of otherconcepts of my invention in which Figures 11A, 11B and 11C show processand apparatus for carrying out the vacuum distillation of a distillablematerial without the need for contacting vapors, from flashing, withsprayed atomized droplets to remove entrainment therefrom prior tocondensation of any vapor, i.e., specifically illustratingm'aintainingsuflicient vapor residence time so that a portion or allentrainment can settle from the vapors prior to the said condensation;and also, contacting the entrainment-containing vapor with relativelycoo-l spray so that a portion of the vapor is condensed and entrainmentis concomitantly settled therefrom together with resulting condensate.Figures 11A, 11B and 11C together are illustrative of another concept ofmultiple stage reduction of this invention, i.e., distilling adistillable material in one or both vessels (11A1or 11B), of afirst-stage reduction and then subjecting first-stage residuum productto further reduction in a second stage (vessel llC). Figure 11D isillustrative of a series of steps comprising visbreaking, recyclecracking, and a final reduction, particularly applicable to furtherprocessing of residual second-stage product of the 2-stage reduction ofFigures 11A, 11B and 11C. Figure ll, inclusive of Figures 11A, B, C, andD, is thus illustrative of a combination of process and apparatus forpreparing a hydrocarbon oil feed and subjecting same to vacuum reductionin a plurality of separate stages, and for further processing resultingresidual product in a series of visbreaking, recycle cracking and vacuumreduction steps to produce a final (high meltingrflsiduum pitch product,

together with light hydrocarbon product, particularly hydrocarbonsboilingin the gasoline range. The baflle sections, i.e., adapted todeflect liquid particles entrained in vapors passed therethrough,illustrated with reference to Figures 3, 4, 5, 8 and 9 are illustrativeof those that can also be employed in conjunction with apparatus ofFigures 11A, 11B, 11C, and 12 and 13 discussed hereinafter. Theillustrated forms of section III of Figure 1, as illustrated in Figures1 and 7 are also illustrative of spray, dam means, and the like employedin the central chamber sections of Figures .11B and 110. Figure 12 isillustrative of still another form of central chamber section (such assection III of Figure 1, section 11b of Figure 11B and section 1110 ofFigure 1 1C) that can be employed. This latter arrangement of spraysprovides for concurrent flow contact of vapors with condensing spray,thereby providing for improved low pressure drop across the distillationchamber at high vacuum. Figure 13 illustrates a distillation chamber andits operation, in which entrainment in vapors from flashing is removedat least in part, by settling, and resulting vapors are condensed inconcurrent flow contact with condensing sprays; the latter is alsoillustrated by Figure 12. Figure 13 is illustrative of one form ofapparatus and process employing the spray nozzle assembly of Figure 12,as applied to a third stage reduction of a hydrocarbon oil.

Although the illustrated embodiments of my invention refer to the vacuumdistillation of a residual hydrocarbon oil, it is to be understood thatmy invention is not limited to the distillation of such oil but isapplicable to the distillation of any distillable material such as forexample vegetable, animal and mineral oils, distillable organic andinorganic chemical mixtures or solutions and juices;

such as in low-temperature flash distillation of water from fruit andvegetable juices as, e.g., in the concentration of orange or othercitrus juices by flashing water therefrom. It is to be understood thatthese drawings are diagrammatic and may be altered in many respects bythose skilled in the art and yet remain within the intended scope of myinvention.

Referring to Figure l, a residual hydrocarbon oil is admitted from lines10 and 11 directly into feed accumulator 12 for charging to thedistillation system.

In one embodiment, virgin petroleum crude is admitted from line 10 intocrude topping tower 13, wherein a lighter crude oil fraction comprisinglight and heavy gas oils, gasoline, and a residual fraction areseparated, the former being withdrawn from tower 13 through line 14 andthe latter through line 16. Virgin topped crude in line 16 is passed tofeed accumulator 12 via line 11, or preferably passed to topped crudecracking system 17 via line 18. Oil residuum cracking product iswithdrawn from cracking system 17 through line 19 and is charged to feedaccumulator 12 via line 11. Other cracking product in cracking system17, is withdrawn via line 15. Accumulator 12 is maintained at aboutatmospheric pressure and any vapors to be vented are discharged throughline 21. Steam can be admitted to accumulator 12 through line 22 tostripout any traces of light ends and thereby reduce the load on the vacuumproducing means in the distillation step to be described hereafter.

Oil charge stock such as a reduced crude, fuel oil, cracking stillresidue, cylinder stock, cracked topped crude or the like, as forexample a residuum from topped crude cracking having a gravity withinthe limits of to 5 API and a viscosity at 210 F. generally above 20 SP8,is withdrawn from accumulator 12 through line 23 and is passed into feedheater 24, where it is heated to a predetermined temperature generallysuitable for, vacuum distillation of same described hereinafter, such aswithin the limits of from 600-900 F. under a presfrom heater24 throughline 26 into vacuum distillation chamber '27, the structural details ofwhich are further described hereafter. t

Vacuum chamber 27, in a preferred embodiment, is horizontally disposed,and is heavily insulated'by external insulation means 9 and ismaintained at an'absolute pressure preferably not exceeding 21 mm. Hgabsolute, and often within the limits of 0.01 to 18 mm. Hg.Thedistillation pressure in chamber 27 is maintained by any desiredvacuum producing means maintained in communication with the interior ofchamber 27 at a downstream point described hereafter, such as a systemof steam jets 28. e r

Liquid charge from line 26 is introduced into flash vaporization sectionI of chamber 27 from an open-end pipe or as a spray in any desireddirection, or preferably as a spray through spray assembly 29 comprisedof one or more spray nozzles, in a direction toward a liquid coalescingscreen such as a wire mat 31, intermediate spray assembly 29 and theupstream end of closure 30, under suflicient momentum to carry theunvaporized feed droplets into the porous matted area which is of suchdepth that liquid is arrested therein and allowed to flow out of thematted formation by gravity. Wire mat 31 is preferably supported in theend portion 30 by support means 35. In this manner, charge emittedtoward mat 31 from spray nozzle system 29 is caused to suddenly reverseits direction of flow, and separation of unvaporized portions from thevaporized portion is thereby greatly accelerated, and sprayed dropletsnot vaporized coalesce on mat 31'with a minimum of splashing, therebylessening the amount of liquid entrained in vapors in section 1.Discharge of the oil feed spray in section I in this manner also causesunvaporized droplets to flow against the flow of hot vapors whichfacilitates further vaporization of those liquid charge droplets, thusfurther providing for a decreased yield in residual unvaporized charge,and for increasing the yield of clean light oil distillates.

Removal of entrained unvaporized material from the vapors is alsofacilitated by the impingement of the sprayed feed upon the entrainedmaterial. Important factors in the introduction of the feed appear to be(1) the distance of the sprays from the wire mat or other such surfacecontacted, (2) the velocity of the liquid droplets with respect to thevelocity of the vapors and the entrained material therein and (3) thediameter of the sprayed droplets. The distance of the sprays from thewire mat is critical inthat the time allowed for effecting the desiredvaporization is not sufficient to permit the atomized droplets to bereversed and to be re-entrained. The velocity is closely related to thisdistance for the same reason. Smaller diameter particles will afford agreater area and a shorter path for diffusion of the vapors or gasesfrom the liquid droplets. Variation of one or more of these factors isutilized to obtain the best results in the operation of this system.

A portion of the unvaporized material in section I settles therein asliquid product. The portion of unvaporized material not settled asresidual pitch in section I is entrained in a highly dispersed state inthe vapors therein, appearing generally as a mist or a fog. Vapors fromsection I passed downstream from spray nozzle means 29, contain theseentrained droplets which must be removed in order to produce clean, lowcarbon residue distillates. This is done by passing the vaporsdownstream in distillation zone 27 from section I into adjacent sectionII through perforate or baflle section 32 and against the flow of an oilspray in section II from spray nozzles 34. Perforate section 32, withdam 33 described hereafter, transversely closes shell 8. Section 32comprises a plurality of openings disposed in at least two separateplanes, each said plane extending in a longitudinal direction andpreferably parallel with the other. 'Such openings in each plane aredisposed from the openings in an adjacent plane, to provide as high as apercent opening between: sections I and II and to: provide further a.circuitous path" for vapor flow tlierethrough. Section 32'. in. a.preferred. embodiment; comprises a system of anglermembers as.illustrated. and described with. respect to the drawings hereafter. Therequisite structure of section. 32 issuch that vapors can be passedthrough it and oil spray impinging upon it will not pass through it.Pressure drop across bafile 32is a fraction of a mm. Hg, generally lessthan about 0.5 mm. and often as low as 0.05 mm; The structure of bafflesections 42, 77 and 63, described hereafter, are similar to or can bethe same as that. of section 32;

Spray nozzle assembly 34- in section II is disposed so astodeliver oilspray in. a direction toward perforate section 32. Atomized droplets ofoil are delivered from spray nozzles 34. at a momentum higher than thatof the entrained liquid droplets in the vapors contacted therewith andimpinge against those entrained droplets whereby the atomized dropletsand impinged droplets are caused to settle from the vapors as liquid insection II. The operation of the sprays 34'2 in section II is criticalin obtaining the. desired results. It involves the problem of properlycontrolling the relative momentum of the feed vapors and the sprayedliquid droplets. In section II the liquid droplets being sprayed againstthe direction of vapor flow impinge upon entrained droplets in the vaporstream. When this impingement occurs there is an ex change of momentum.If the sprayed droplets have the greater momentum the direction of flowof the entrained droplets will be reversed; if the momentums of the twodroplets are equal the resulting momentum will be zero and the combineddroplets will tend to fall to the bottom of the vessel. If, however, theentrained droplets have the greater momentum, the direction of flow ofthe sprayed droplets will be reversed with a resulting increase inentrainment. The ratio of the momentum of the blanket of spray to themomentum of the vapor stream, including the entrained mist containedtherein is at least 1:1. This ratio may be between 1:1 and 125:1, but ispreferably at least 3:1.

The temperature of the oil spray from spray nozzles 34 is maintained ata level very nearly the same as that of vapors contacted therewith. Itis important that these spray temperatures be at least as high as thevapor tern pera-tures, for oil spray temperatures lower than the vaporscontacted cause some condensation of Vapors not preferred in thisembodiment of my invention. In most cases in order to obtain maximumefficiency it will. be necessary to keep the temperature of the oilspray from nozzles 34 above that of the entering vapors to offset heatlosses by radiation and thereby prevent condensation in section II.However, in some instances for special purposes it may be desirable toeffect some condensation in section II in which case the spraytemperature is adjusted accordingly. In sections in which partialcondensation takes place, it is preferred to maintain the initialmomentum of the sprayed dropletssulficiently high that even afterabsorbing momentum, through condensation of some of the vapors travelingin the opposite direction, the resulting momentum will still be at leastas great or greater than that of the vapors or any liquid dropletsentrained therein, otherwise excessive entrainment of condensate willoccur. Oil charge to spray nozzles 34 is pro vided by withdrawing aportion of the settled liquid from the bottom of section II andrecycling same to spray nozzle system Total liquid is withdrawn throughline 3d via pump 37, and line 41. Se tled' liquid from section II, forrecycle to spray nozzle system 34, is passed from pump 37 to spraysystem 34 via line 35% and heater 39, generally a steam heater. Oil inheater 39 is heated to a temperature generally of from about 15 to 30 F.above that of the vapors passed through perforate section 32. Materialpassed through line 41 is substantially the same material as settledliquid in section I. Ifthe temperature of oil from spray nozzles 34 islower thanthat of vapors passed; through section; 32., somecondensatefli'ay be formed and. collected with residual pitch product.in section II. In such instances it is sometimes. advantageous torecycle liquid from line 41 to section I via line 40, accumulator 12,heater 24, and line 26. When: liquid from line 41 is the same as thatdescribed hereafter as settled in section I, these two streams can becombined for further treatment to be described.

Vapors passed downstream in section II from spray nozzles 34 are free ofentrained liquid and comprise vapor fractions of clean gas oils to berecovered as described hereafter. These vapors are passed from. sectionII into adjacent and downstream section III through perforate section 42against. a flow of atomized oil sprayed from spray nozzles 44. Spraynozzle assembly 44is disposed in section III so as to deliver oil sprayin. a direction toward perforate section 42, and is preferably thesamein design as system 34, described in more detail hereafter. Perforatesection 42 with dam ring 43 transversely closes vessel 27 at a pointintermediate nozzle assemblies 44 and 34. Oil from spray nozzles 44 ismaintained at a. temperature lower than the temperature of vapors beingpassed from section I I through perforate section 42 so as to causesubstantially total condensation. of those vapors upon contacttherewith. The temperature of oil emitted from spray nozzles. 44 isdependent on the specificdistillation conditions employed, but isgenerally with the limits of 3 and 500 F. lower than that of the vaporscontacted therewith. The momentum of the atomized oil droplets ejectedfrom spray nozzles 44 is maintained greater than that of the vaporscontacted therewith, whereby the atomized droplets with condensatethereon and impinged entrained droplets are caused to settle and toaccumulate in the bottom of section III. Total condensate collected inthe bottom of section III including that described hereafter, iswithdrawn through oil outlet 46 via pump 47", and in part through lines48 and 49, and in remaining part as required. in. spray nozzle assembly44, and 51 described hereafter, through cooler 52, line 53 and header54. Oil in cooler 52 is cooled to the necessary temperature lower thanthat of vapors passed through perforate section 42 sufficiently toprovide for total condensation as described. Condensate withdrawnthrough line 49 is a distillate product of the process.

As described hereinabove, the operating pressure in section I is higherthan that in any other section in vacuum chamber 27 for reason that mostof the vapor-s present in chamber 27 are in section I. Consequently agradual pressure drop is eliected and each section downstream fromsection I operates at a lower pressure than the preceding or upstreamsection. In this specific em bodiment illustrated, section III is indirect communication with evacuation means 28 and is under the lowermostoperating pressure in the chamber. Sections IV and V are each at a lowerpressure than that of section I. Settled residual pitch product fromsection I is withdrawn through line 56 either alone or combined withliquid from line 41 and is discharged through pump 57' and line 58 intosection V which is the opposite most section in chamber 27, andoperating at a pressure lower than that of section I. Liquid from line58 is introduced into section V, which serves in this embodiment as asecond flash vaporization section, as a spray through spray nozzlesystem 59, similar in design to spray system 29, in a direction toward(an upstream direction with respect to the path of flow), a wire mat, orcoalescing means 62 similar in structure to wire mat means 3 1. Wire mat62 is preferably supported in end closure 61 of chamber 27. Liquidcharge admitted into section V is caused to suddenly reverse itsdirection of flow so as to minimize the amount of entrained liquid invapors in section V in the same manner as carried out with respect tothe charging operation in section I. A portion of the material insection V is unvaporized and settles therein as liquid and comprises a.higher softening point pitch product than that settledin section I. Inthis embodiment, this step may be effected without supplemental heatingand while utilizing the inherent pressure drop through chamber 27without the need for any supplemental pressure reducing means. Operatingpressure in section V is often a fraction of a mm. Hg pressure and is asmuch as 15 mm. Hg absolute lower than that in section I, therebyeffecting a substantial and significant flash vaporization to pro duce ahigher softening point pitch in proportionately reduced yield togetherwith an increased yield of desirable clean gas oil, the latter beingsuitable as charge stock to various hydrocarbon conversion processsteps. The portion of unvaporized material not settled as liquid insection V is entrained in the vapors therein in a highly dispersedstate, which vapors are passed from section V downstream into section IVthrough perforate section 63 of design similar to that of perforatesections 32 and 42, and against the flow of an oil spray in section IVfrom spray nozzle system 66, of design similar to that of nozzle system34, and disposed to direct liquid spray toward section 63. Spray fromnozzles 66 comprises atomized oil droplets having a momentum higher thanthat of entrained liquid droplets in contact therewith and impinge thoseentrained droplets whereby the atomized droplets and impinged dropletsare caused to settle in section IV. The operation of sprays in sectionIV is the same as that described with respect to the operation of spraysystem 34 in section II. Accordingly the temperature of oil spray fromspray nozzles 66 is maintained at a level very nearly the same as thatof the vapors contacted therewith and preferably is at a temperature offrom to 30 F. higher than the vapors contacted therewith. Settled liquidin section IV is under some conditions of operation the same as settledliquid in section V and comprises pitch of increased softening point,i.e., relative to pitch product of section I. Settled liquid iswithdrawn from section IV through line 67 via pump 68, in part returnedas feed to oil spray system 66 via line 69, heater 71 and line 72. Oilin heater 71 is heated to the requisite temperature described above.Remaining liquid from pump 68 is discharged through line 73 either asseparate product via line 70, or combined with residual oil withdrawnfrom section V via pump 74 and line 76 or recycled to section V via line58. Residual pitch withdrawn from section V and discharged through line76, comprises the high softening point pitch product of my process.Vapors in section IV, passed downstream from spray nozzles 66, are freeof entrained liquid and comprise vaporous fractions of clean gas oils tobe passed into section III and are totally condensed in section III.These vapors are passed from section IV downstream through perforatesection 77 simi lar in design to perforate sections 32, 42, and 63,against a flow of atomized oil sprayed from nozzles 51 in section III,intermediate spray system 44 and perforate section 77, and adapted todirect liquid spray in a direction toward section 77. Oil droplets fromspray nozzles 51, maintained at a temperature sufficiently lower thanthat of vapors to be contacted therewith have a momentum sufiicientlyhigh such that even after absorbing momentum from the vapors contactedthe resulting momentum will still be at least as great or greater thanthe vapors or any liquid droplets entrained therein. Such droplets ofentrained condensate are then removed by impingement of the sprayeddroplets thereon, and total condensate formed settled in the bottom ofsection III and is withdrawn from section III together with othercondensate formed as described above, through line 46, and comprising aportion of the distillate product of the process.

Although substantially total condensation is effected in section III,scrubbing means 79 is positioned intermediate vacuum pump 28 and sectionIII in order to prevent delivery of any condensate particles directly tothe vacuum pump, thereby maintaining the efficiency of the evacuationsystem at the desired level. Scrubbing system 79 comprises anyconventional scrubbing means employing a scrubbing liquid, as forexample a heavy hydrocarbon oil flowing in counter-current contactrelation with the vapors to be scrubbed. Fresh absorption oil, forexample, can be introduced into zone 79 through line 81 and withdrawnthrough line 82 via pump 83 and recirculated via line 81, or via line 80and cooler 85. Oil can be withdrawn from the system via line 84, ifdesired. Vacuum producing means 28, e.g. a steam jet, communicates withsection III via line 90, scrubber 79, and vacuum line 75.

With reference to Figure 1, I have illustrated one embodiment of myinvention whereby the residual flash vaporization pitch product formedinitially in chamber 27 can be flash vaporized in the same systemwithout the need for supplemental heating or additional applied vacuum.It is by virtue of the inherent pressure drop through chamber 27,developed as I have described, by means of which this feature of myinvention is made possible Another embodiment of my invention isillustrated with reference to Figure 2 wherein the residual pitchdistillation product is withdrawn from the initial flash vaporizationsection and further flash vaporized in a flash vaporization zoneexternal to the zone of the initial flash vaporization. In thisembodiment the external or secondary flash vaporization step ismaintained in direct communication with a downstream section of theinitial distillation zone and is thereby maintained at a pressure lowerthan that of the initial flash vaporization. Referring to Figure 2,residual hydrocarbon feed from line 26 is introduced into flash sectionI of a horizontally disposed chamber 27 through spray nozzle assembly29, similar in design to nozzle assembly 29 of Figure l and adapted todirect liquid spray in a direction towards coalescing means 31. Pressureconditions in chamber 27 are similar to those maintained in vacuumdistillation chamber 27.

As described with reference to the embodiment of Figure 1, a portion ofthe charge is vaporized in section I. A major proportion of theunvaporized material settles in section I and comprises a high softeningpoint residual pitch product. The portion of unvaporized material notsettled in section I is passed entrained as droplets in vapors fromsection 1 into adjacent section II, through perforate section 32 similarin design to section 32 of Figure 1, against the flow of oil spray insection II from spray nozzles 34. Spray nozzles 34, which can be thesame as those of nozzle system 34, are adapted to direct spray in adirection toward section 32. The operation in section II of chamber 27is the same as that described above with reference to chamber 27 insection II with respect to spray temperture, momentum of the atomizeddroplets, and settling of entrained liquid. Settled liquid in section IIis withdrawn through line 91 via pump 92 and passed in part via heater39 to spray nozzles 34 and, in remaining part is withdrawn from thesystem through line 41. When the temperature of oil spray in section IIis very nearly the same or not more than 30 F. higher than that ofvapors contacted therewith, settled liquid in line 41 is very nearly thesame as that in section I and can be combined with the latter if desiredfor use in a manner as described hereafter. Vapors passed downstream insection II from spray nozzles 34 are free of entrained liquid andcomprise vaporous gas oil fractions. These vapors are passed fromsection II into adjacent and downstream section III through perforatesection 42 against a flow of atomized oil sprayed in section III fromspray nozzles 44, adapted to direct oil spray toward section 42.Perforate section 42' is similar in design to section 42 of Figure 1.Oil spray from nozzles 44 is maintained at a temperature lower than thetemperature of vapors passed from section II through perforate section42', preferably from 5 to F. lower so as to cool and condense a portionof those vapors. The condensate is formed in section III as describedabove with respect to the formation of condensate in section III inchamber 27. Condensate is withdrawn from section III through line 46 viapump 47 and passed in part to spray system 44 through cooler 52, whereinit is cooled to the oil spray temperature required in section III, andin remaining part is discharged through line 49. Uncondensed vapors freeof entrained liquid are passed from section III into adjacent section IVthrough perforate section 93 similar in design to perforate section 42and section 32', against a flow of oil spray emitted from spray nozzles96 adapted to direct liquid spray against section 93, and to alsodisperse it in other directions throughout section IV. It is desiredthat in section IV the maximum condensation be offected, i.e., thecondensation of all remaining condensable vapors. It is important that asufficient amount of oil spray be discharged from spray nozzles 96 at adesired low temperature to complete the condensation of all remainingcondensable vapors in contact therewith. It is often advantageous thatthe temperature of the oil spray from spray nozzles 96 be as low as 100F. Total condensate formed in section IV is withdrawn through line 97via pump 98 and recycled in part via cooler 99 to spray nozzles 96, andpassed in remaining part through line 101. If desired, totalcondensation in section IV can be effected under these temperatureconditions by positioning baflie section 93 downstream from spraynozzles 96, and then directing oil from nozzles 96, only toward baffle93 downstream therefrom (and also toward conduit 112 as shown). In sucha case, total condensate is collected upstream from baffle section 93employing a dam in vessel 27 to prevent flow of total condensate thusformed into section III.

Settled liquid from section I is withdrawn through line 102 via pump 103and lines 104 and 105 to secondary reduction chamber 106. Residualliquid discharged from pump 103 is passed alone or in admixture asdesired with liquid from line 41 introduced into line 104- through line107. When desired, any portion of liquid in line 104 can be withdrawnfrom the system directly through line 108. Secondary vacuum chamber 106is maintained in direct communication via line 109 with the interior ofat least one downstream section of distillation chamber 27'. In thismanner, these latter sections in chamber 27' operating under highervacuum than that employed in section I inherently provide for a vacuumin chamber 106 higher than that in section I of chamber 27. Accordingly,settled liquid from section I passed into chamber 106, is further flashvaporized therein without the need of supplemental pressure reductionand without further heating,

to provide further yields of gas oil fractions, and higher softeningpoint pitch in correspondingly lower yield. Vapors formed in chamber 106are discharged therefrom via line 109 into at least one of sections II,III or IV through lines 110, 111 or 112 respectively. Whether or notvapors are discharged into all three sections or one selected section isdependent on the particular operating conditions employed in chamber 27which in turn affects the operating pressure in chamber 106, and thecomposition of vapors dischargedthrough line 109. Generallythecomposition of distillate from chamber 106 (in line 109) is thedetermining factor, such vaporous distillate being returned into thatsection of chamber 27 containing settled liquid most nearly the same incomposition thereto. In any case vapors passed into either sections II,III or IV are contacted with oil spray emitted from one or more nozzles34, 44 or 96, respectively, as the case may be, under conditionsproviding the same sprayvapor contacting already in progress in thatsection. Residual pitch product of high softening point is withdrawn asa product of the process from chamber 106 through line 113.

In this embodiment vacuum reducing means 28 is in direct communicationwith section IV of chamber 27,

14 section IV being the downstream-mostportion and 015- erating at thelowest pressure in chamber 27.

A preferred form of the perforate bafile sections 32, 42, 77, and 63 ofFigure l and 32', 42' and 93 of Figure 2, is illustrated with referenceto Figures 3, 4, and 5. As illustrated in these figures baflle section42 comprises a plurality of parallel courses of angle irons, each saidcourse substantially closing said chamber, angle irons in each of thesesaid courses facing a common direction transversely across said chamber,and each angle in each course having its vertex positioned within thesides of the adjacent and preceding angle. Dam ring 43 (Figures 4 and 5)serves as a partial support for the angle iron baiifie section 42 andalso to prevent channeling of vapors from section II to section III,i.e., thereby causing vapor to pass only through the circuitous pathprovided by baffie assembly 42. Seal rings 121 in conjunction with.fastening means 122 provide for further supporting baffle section 42.Figure 4, shows baffle section 42 to consist of. two courses of angleirons each transversely crossing chamber 27, and Figure 5 shows therelative position of angles in each course making up the baffle section42. As illustrated in Figure 5, the angle irons in all courses face acommon direction transversely across the chamber 27, and each angle ineach course. has its vertex positioned within the sides of the adjacentand preceding angle. Preferably, the sides of the angles in each courseare parallel with the corresponding sides of the angles in the adjacentcourse. Dam rings 33, 78 and 60 of Figure l, and 33', 43 and 94 ofFigure 2, are preferably the same as dam ring 43 specificallyillustrated in Figure 5.

Figure 6 is illustrative of one system of spray nozzles utilized in thepractice of my invention. Figure 6, shows a portion of the spray nozzleassembly .34 in Figure 1 by means of which the oil spray is disperseduniformly against the flow of vapors passing against it from bafilesection 32. It is to be understood that this invention is not limited tothe particular spray system illustrated, the requisite being a sprayassembly capable of spraying the spray in each section in a manner so asto uniformly distribute liquid through the vapors contacted therewithand to completely blanket the path of the vapors. It is advantageousthat each spray nozzle system illustrated in either chambers 27 or 27 bespaced away from the re speotive bafile section or wire mat, with whichit is associated so that it is at a distance from the plane of the faceof the ba-fiie or mat of from 0 to 2 feet, but preferably less than 1foot. Although two banks of spray nozzles are shown in each location, itshould be understood that one bank may be used or more than two, ifdesired.

Figure 7 illustrates an alternate form of section III in chamber 27. Inthis embodiment dam 50 is positioned so as to maintain the condensateformed as a result of contacting vapors passed through bafiie section 42with sprayed oil from spray assembly 44, separate from condensate formedby contacting vapors passed through baffle section 77 with oil sprayfrom nozzle assembly 51. As illustrated in Figure 7 separate distillatesare withdrawn through lines 46a and 46b. In this embodiment separate oilstreams are fed to the respective oil spray systems. Oil charged throughspray assembly 51 is withdrawn from section III through line 46a, viapump 47a, and line 48a, and returned to sprays 51 via cooler 52a, andline 53a. Similarly, oil charged through spray assembly 44 is withdrawnfrom section III through line 4617 via pump 47b, and line 43b, andreturned to sprays 44 via cooler 52b and line 53b. Condensate product iswithdrawn from line 46a via line 49a, and through 46b via line 4%.

Figure 8 is illustrative of a baffle means alternate to guard chambermeans 79 of Figure 1, for preventing the escape of any entrained liquiddroplets from section III into the vacuum producing means 28. As shownin Figure 8, guard chamber or baflle section is an assembly of angleirons disposed in two separate courses (see also the plan. view ofFigure 9) disposed so as to -which reduce the severity of initialentrainment.

- provide a circuitous path therethrough. In this respect the bafiiesection 130 is similar in design to the baffle sections of chamber 27and 27 described in detail with reference to Figures 3, 4, and 5, above.Vapor outlet 131 is disposed in the side of guard assembly 130 in gastight communication with vacuum producing means 28. Liquid outlet 132 isprovided in the bottom of baffle section 130. In the operation of thisembodiment, uncondensed vapors in section III before reaching vacuumproducing means 28 are forced to pass through the batiie section 130,thereby causing the vapors to follow a circuitous path so as to knockout any entrained droplets. Any liquid thus separated, is collected inthe bottom of the section 130 for withdrawal through conduit 132. Baffleassembly 130 is preferably located centrally in section 'III. Figure 9is a plan view (see line 9-9 of Figure 8) showing a preferredarrangement and design of the baiflies in section 130.

As is the case in operating many petroleum processes, it is important inthe practice of the present invention to provide means for compensatingagainst expansion and contraction of lines carrying hot oil streamsunder high vacuum. Such a compensating means is the expansion jointassembly illustrated in detail with reference to Figure 10, whereinexpansion joint assembly 140 is a bellowstype expansion joint comprisingsealed diaphragm 141 disposed in the hot oil line 142, line 142 beingexemplary of any line in the process system illustrated in Figures 1, 2,11A, 11B or 11C, carrying hot oil under high vacuum such as lines 56,36, 46, 67 and others, in Figure 1, and lines 102, 91, 46, and others inFigure 2. Diaphragm 141 contains concentric support ring 143 mountedinternally to prevent collapse of the diaphragm 141 due to an increasein vacuum within the piping system. Support ring 14-3 is adapted toprevent collapse of diaphragm 141 due to the force of atmosphericpressure, without interfering with the ability of the diaphragm toabsorb expansion.

I generally prefer to maintain the momentum of the sprayed droplets ineach of the sections of the distillation zone sufliciently higher thanthat of the entrained droplets contacted therewith, so that the sprayeddroplets carry on through and impinge upon the aforesaid baffle section,as for example, sprayed droplets from spray system 34 against the battlesection 32; however, when substantially total condensation is effected,the relative momentum of the sprayed droplets and the entrained dropletsis not of primary importance. In this manner the function of the battlesection is to coalesce the spray, carrying with it the coalescedentrainment, i.e. droplets entrained in the vapors contacted with thespray, causing the coalesced materials to drain to the bottom of theba-flie section. It appears that it is the surface tension of the oil onthe surface of the batlle section that prevents reentrainment of liquidinto the high velocity vapor stream.

In another embodiment of my invention, a portion of settled liquid fromsection I is returned into section I as a spray 2% directly behind spraysystem 29, and sprayed droplets from spray 29, and from the saidreturned spray system 2% in section I, are sprayed toward wire matcoalescing means 31. In this manner, unvaporized feed portions entrainedin vapors in section I formed as a result of the initial flashvaporization of feed ejected from. spray system 29, are impinged withadditional sprayed droplets under conditions of momentum alreadydescribed, so as to cause all such entrainment to settle in section I.If desired, total vapor from section 1, free from entrained liquid, canbe condensed, thereby eliminating the need for bafile section 32,partition 33 and spray assembly 34, pro viding for a still lowerpressure drop across chamber 27. Such operation is well applied atgenerally lower flow rates, or when other operating conditions areemployed In the present embodiment, however, the temperature of liquiddroplets sprayed from system 34 in section 11 (Figure 1),,

is maintained slightly lower than that of vapors contacted therewith, soas to cause partial condensation of vapors passed through baffle section32 and settling of same in section II, and thereby for recovery of anadditional distillate product fraction. Similarly, settled liquid fromsection V of Figure 1, and from section I of Figure 2 can be directedinto these respective sections'at a point positioned behind spray means59 and 29' respectively to provide for settling in those sections of allentrained unvaporized feed portions, and for recovery of an additionaldistillate fraction in the respective downstream section, or, ifdesired, baffle sections 63 and 32' together with spray assemblies 66and 34' respectively can be dispensed with.

The high softening point pitch product of my invention particularly thatwithdrawn as settled liquid from section V of chamber 27 (Figure l), andfrom secondary vacuum reduction chamber 106, through line 113 (Figure2), is sufliciently devoid of vaporizable materials that it can be usedin admixture with coal to produce a coal-coke of increased mechanicalstrength without substantial contamination of aromatic by-products ofthe coal coking process. It is also characterized as being very low inmaterials insoluble in carbon disulfide.

In one embodiment of my invention I have provided for conducting theflash vaporization steps of my process at temperatures lower than thoseutilized hereinbefore without the need for reducing the pressureproportionately. The practice of this embodiment is accomplished bycharging the oil feed in a sufiiciently high finely divided, or atomizedstate so that the liquid feed particles have an extremely small radiusof curvature; the feed is atomized in the flash vaporization chamber sothat the average radius of curvature of the liquid feed particles isless than 0.1 micron, preferably from 0.01 to 0.001 micron. In atomizingthe feed particles in this manner, a larger amount of vaporization iseifected than would be indicated by the normal vapor pressure curve,characteristic of that feed material, and an amount of vaporization isobtained at the operating pressure level of my process comparable tothat obtained when charging feed droplets of larger radius of curvatureat absolute pressure as low as about 20 microns. In this embodiment, atthe operating pressure, vapors in equilibrium with the atomized feeddroplets will have a density often as high as 1,000 times greater thanthat of vapors in equilibrium with larger radius droplets at pressure aslow as about 20 microns absolute pressure. Also the vapor in equilibriumwith the atomized feed droplets will be approximately 250 F. cooler thanindicated by the normal vapor pressure curve. Atomizing the liquid feedin this embodiment eliminates the necessity for superheating the feed toobtain vaporization, and the concomitantly increased density of thevapors results in decreased vapor velocities; and it is possible tooperate the vacuum chamber while obtaining the operating advantagesgenerally possible only at much lower pressures, while at the same timepreventing the high vapor velocities that are characteristic of normaloperation.

With reference to Figure 11, a hydrocarbon oil, such as a virginpetroleum crude is introduced into preheat furnace 151 via line togetherwith steam introduced via line 153, and heated in preheater 151 to apredetermined temperature suitable for distillation describedhereinafter, such as within the range of 600-900 F., and passed tovacuum steam stripper 152 together with steam from preheater 151., alsoheated to withln the said temperature range.

In vacuum steam stripper 152 a gasoline streamus sep arated, anddischarged via overhead line 15; a side out of gas oil is separated, andwithdrawn via line 156; and a bottom residuum product, generallycontaining some gas oil, is withdrawn via line 153. Residuum in line 158at a temperature within the predetermined range is introduced intochamber In of elongated distillation vessel 157,

preferably disposed substantially horizontal, under flashing conditionsso as to vaporize a portion of the said residuum. Residuum from line 158is preferably introduced into section la in an upstream direction, i.e.,toward end section 159 as a-spray, from nozzle assembly 150a, against aliquid coalescing surface such as that provided by a wire mat 161.Advantages of this method of feed introduction are set forth herein,with reference to Figures 1 and 2. However, feed from line 158 can beintroduced into section Ia from an open end pipe against a coalescingsurface; or, in lieu of a coalescing surface, from an open end pipe oras a spray, in any desired direction. Vapors formed in section Iacontain entrained liquid droplets or particles, comprising unvaporizedportions of the residuum feed, which, if not removed from the vaporsprior to condensation, will be present in the condensate as undesiredimpurities, as discussed hereinabove with reference to Figures 1 and 2.Vapors from section Ia of chamber 157 are passed through baflle section162, which can be similar in design to battle sections of Figures 1 and2, further illustrated with reference to Figure 3, 4 and 5; transverselyclosing chamber 157 and supported by darn ring 163 and adapted todeflect liquid droplets present as entrainment in vapor passedtherethrough. Dam ring 163 also provides for confining liquid product insection Ia, i.e., prevents its passage into section Ila. Dam ring 163also prevents unvaporized liquid in section la, adhering to the innerside wall of that chamber section and moving downstream, from passinginto section Ila to thus contaminate liquid product therein, and causesliquid contacting same to accumulate in section Ia.

Vapors containing entrained droplets not deflected therefrom by bafliesection 162 are passed against a flow of atomized droplets emitted fromspray nozzle means 164, the latter spray being maintained at atemperature lower than that of vapors contacted therewith so as toeffect partial condensation of same and to concomitantly causeimpingement of sprayed droplets with condensate droplets and entrainedparticles and settling of the resulting impinging and impinged dropletsin section Ila. Preferably the momentum of the atomized droplets emittedfrom spray 164 is at least equal to that of condensate droplets formedplus that of entrained particles contacted therewith, so that dropletsof condensate and entrained particles are settled from vapors in sectionIla prior to the flow of vapors from section Ila. However, if desired,the momentum of sprayed droplets from nozzle assembly 164 can be lessthan that of the entrained particles plus condensate droplets formed insection Ila, when section Ila is of sufficient length to permit settlingof the impinged and impinging droplets prior to passage of the vaporstherefrom into section Illa. Vapors, free from entrainment are passedthrough bafile section 166 transversely closing chamber 157, which canbe similar in design to baffle section 162, and are contacted in sectionIlla with atomized liquid droplets emitted from spray nozzle assembly167, the latter at a temperature sufficiently below that of the vaporscontacted therewith so as to effect substantially complete vaporcondensation in section Illa. Momentum conditions of the atomizeddroplets from spray assembly 167 are preferably such that impingingspray and impinged total condensate formed in section llla are caused tosettle therein as liquid product. Vapors, free from entrained condensateare passed from section Illa through baffle section 163, transverselyclosing chamber 157, and which can be similar in design to baffle 162,baifle 163 serving as a deflector of any remaining liquid droplets invapors passed therethrough. Any vapors, i.e. uncondensed in sectionIlla, passed through baffle section 168 into section IVa are removed viainternal guard chamber 169, similar in design to haffle system 136 ofFigure 8, in any event functioning as a deflector of any entrainedparticles that may be present in uncondensed vapors to be re- 18 movedfrom section IVa via line 171 and steam jets 172. Baffle system 169,which can also be referred to as a liquid-vapor separator can compriseany suitable means such as an assembly of conventional mist-extractorbattles or the like.

During residence of vapors in section Ia, some entrainment settles inthe bottom thereof as product together with a major portion of theunvaporized liquid charge. Liquid product settled in section la,comprises residuum product of the distillation in chamber 157 and iswithdrawn from section Ia via line 173. Residuum product in line 173 canbe recycled in part to section la via line 174, preheater 176 and line158, i.e., with fresh feed thereto, or directly from line 173 to linefor further preheating in 151 together with fresh feed. Residuum productcan be withdrawn from the system via line 176a and can also be withdrawnvia lines 173 and 177 for charging to a second stage vacuum reductiondiscussed hereinafter.

Condensate formed in section Ila is withdrawn via line 178 and recycledin part via cooler 179 and line 181 as feed to spray nozzle assembly.164, thereby providing liquid product from section Ila as the source ofliquid spray emitted from nozzle assembly 164. The remaining portion ofliquid roduct from section Ila is withdrawn via lines 178 and 182. Totalcondensate formed in section Illa is withdrawn therefrom via line 183and recycled in part via cooler 184 and line 186 to spray nozzleassembly 167 and emitted therefrom as the said spray. Thus, as in thecase of section Ila, the source of droplets emitted from spray 167 istotal condensate recovered in section Illa.

Although it is only a very minor amount of liquid and vapor that ispassed from section Illa into section IVa, if any at all, any suchliquid collected in section IVa is withdrawn via line 186a.

When desired, the use of a spray in section Ila, in chamber 157, can bedispensed with, with the concomitant advantage of lowered pressure dropacross the distillation chamber 157. The separation of entrainment fromvapors in section Ila is generally not as complete when the said spraysare dispensed with, although some entrainment settles in section Ila,such settling being facilitated by increasing proportionally the lineardimension of section Ila. Also, a small amount of condensation generallyoccurs in section Ila, in the absence of spray from nozzle assembly 164,by radiation therein. Operating in this manner, the pressure drop acrosschamber 157 can be lowered, although, when not employing a liquid sprayin section Ila, some unsettled entrainment, i.e., particles ofunvaporized feed, will be present in condensate recovered from sectionIlla. Although the pressure drop lowering acLieved in any specificinstance is dependent upon the initial operating conditions, i.e., whenemploying a spray, a pressure drop lowering of up to 2 mm. Hg is oftenachieved when dispensing with the use of such spray.

Another fraction of hydrocarbon oil, such as petroleurn crude, isintroduced via line 191 into preheater 192, wherein it is heated to atemperature in a predetermined distillation range as discussed withreference to preheating of oil from line 150, and is then withdrawn vialine 191a and passed into flash chamber 193, wherein a gasoline fractionis separated, and withdrawn via overhead line 194; a gas oil fraction isseparated, and withdrawn via line 196; and a residuum or bottomsfraction is separated, and is withdrawn via line 197, and passed ascharged to elongated vacuum distillation chamber 198, preferablysubstantially horizontally disposed. A portion of charge from line 197is introduced into chamber 198 via line 199 into end section lb, underflashing conditions that can be carried out as described relative tointroduction of feed into section Ia of chamber 157, i.e. as a spray orfrom an open end pipe, in any desired direction, preferably upstreamtoward end section 201, against a coalescing surface such as wire mat202, the latter supported by support means 203 and adapted to be movedin a longitudinal direction in section 1b. A re maining portion ofcharge from line 197 is introduced into the opposite end section Ibunder flashing conditions as described relative to introduction of feedinto section Ib. A major proportion of the unvaporized charge insections Ib and Ib settles in each section as liquid product. Vaporsfrom section 117 containing entrained liquid particles are passedthrough baffle section 207 transversely closing chamber 198 and ofdesign similar to that of baflie section 162 of chamber 157, intocentral section 11b in contact therein with droplets of atomized sprayemitted from nozzle means 288. The temperature of droplets emitted fromnozzles 208 is sufliciently lower than that of vapors contactedtherewith-so as to cause substantially complete condensation of the saidvapors. The momentum of the atomized droplets is sufficiently high so asto cause impinging droplets and impinged droplets of condensate andparticles of entrained unvaporized feed to settle as liquid product incentral section IIb. However, if desired, the said momentum conditionsmay be dispensed with, it being important, in any case, that all theliquid droplets are settled in section IIb as product. Thus, in theevent that the said momentum conditions are dispensed with, section IIbcan advantageously be of sufficient length to permit the said settlingof all liquid droplets therein.

Vapors formed in section Ib contain entrained particles of unvaporizedfeed and are passed through baffle section 209, the latter transverselyclosing chamber 198 and of design similar to baffle section 207, intosection IIb, against a spray of atomized liquid droplets therein fromspray nozzle assembly 211a under momentum and temperature conditions tocause substantially complete condensation of vapors contacted therewithand settling of same withentrained particles. If desired, the saidmomentum conditions of spray from nozzle assembly 211a can be'dispensedwith, it being important, in any event, that all condensate andentrainment be settled in section IIb. Vacuum is applied to the centralsection, i.e., section 1112 of chamber 198 by any conventional means, asfor example by steam jet means 211 connecting with section IIb via line212, external guard chamber 213, and line 214, the latter connectingwith the interior of section IIb at a point intermediate spray nozzles208 and 211a, through internal guard chamber 216; the latter serving asa mist-extractor so as to deflect any unsettled liquid droplets from anyvapors leaving section IIb, so as to prevent their flight to vacuumproducing means 211, such interference with vacuum means 211 seriouslyimpairing its vacuum producing efficiency.

A' preferred form of internal guard vessel 216 is illustrated in thedrawings with reference to Figure 8, the latter specifically referringto its adaptation to apparatus of Figure l, but being also illustrativeof the preferred form of internal guard chamber in section IIb ofchamber 198. External guard chamber 213 comprises a spray and bafflemeans for condensing any residual vapors from line 214 and for arrestingany liquid particles entrained therein. Liquid supplied to the spraysystem in external guard chamber 213 can be any heavy fraction ofhydrocarbon oil, but is preferably liquid, originally withdrawn fromsection IIb and charged to chamber 213 via line 216a, withdrawn via line217 and, when desired, recycled to line 216a, by means not specificallyshown.

Liquid product in section Ib and Y1; in chamber 198 comprisesunvaporized liquid charge and contains any condensate, such as formed ineither section by means of heat radiation, and also particles ofunvaporized charge initially entrained in vapors therein but settledfrom those vapors during the flight of same through section Ib into thecentral chamber section IIb-or through section I'b into section IIb.

Residuum product of distillation, present in section lb of chamber 198iswithdrawn via line 218. A portion of residuum from line 218 can berecycled to section Ib together with fresh feed thereto via lines 219,221, 222, preheater 223 and line 197. If desired, residuum product. fromline 218 can be recycled via lines 219 and 224 directly to preheater 192and sections lb or Ib. If desired, residuum product can be withdrawnfrom line 218 via line 226, or, via line 227 for passage to furtherreduction in a second stage vacuum distillation discussed hereinafter.

Residuum product from section P12 is withdrawn via line 228, and can berecycled to distillation chamber 198 via lines 229, 222, preheater 223,and line 197, or, if desired, via line 228 and preheater 192, todistillation chamber 198. Residuum from line 228 can also be with drawnfrom the system via line 231. If desired, residuum from line 228 can bewithdrawn via line 227 and passed to a second stage vacuum distillation,for further reduction as described hereinafter. Total condensatecollected in section IIb is withdrawn via line 233 and recycled in partvia 234 and cooler 236 to spray assembly 208 as the source of liquiddroplets emitted therefrom; is passed in part from line 233 via line 237and cooler 238 as liquid to be emitted from spray nozzle assembly 211a;remaining condensate being withdrawn from section IIb via lines 233 and239.

Residuum product from distillation chamber 157 or 198, or both, can befurther reduced in a second-stage vacuum distillation system to providea. still higher softening point residual pitch product and higheroverall yields of gas oil distillate. Thus, residuum product from line177, alone, or together with residuum product from line 227, is passedvia line 232, preferably divided as two separate streams, and passedthrough preheater 233a and therein heated to a temperature within apredetermined range for the said second stage distillation such aswithin 600-900 F. A portion of the preheated residuum product iswithdrawn from preheater 233a via line 234a and the remaining portion iswithdrawn via line 236a. Residuum in line 234a is then passed intosection Ic of distillation chamber 237a under flashing conditionstherein, that can be carried out as described relative to introductionof feed into section 1b of chamber 198, i.e. as a spray, or from an openend pipe, in any desired direction, preferably upstream against acoalescing surface such as that provided by wire screen 239a,transversely positioned in chamber 237a intermediate the end of conduit234a in section I0 and chamber end portion 2384'. A major portion ofunvaporized charge settles as liquid in section Ic. Vapors formed insection Ic contain entrained particles of unvaporized charge and arepassed into adjacent section IIc through baflle sections 238a,transversely closing chamber 237a and which can be of design similar tothat of baffle section 162 of chamber 157. Vapors passed from section Icinto section are contacted in the latter section with a spray ofatomized liquid droplets maintained under temperature-momentumconditions so as to effect condensation of a portion. of the said vaporscontacted therewith and concomitantly cause impingement of sprayeddroplets with particles of unvaporized charge and droplets ofcondensate, to cause settling of all liquid droplets in section IIc asliquid product. If desired, the momentum conditions can be such that theforce of impinging droplets is below that causing settling of alldroplets in section 110, in which case it is important that the lineardimension of section He be sufficiently great that these dropletsare-substantially completely settled prior to passing of vapor fromsection IIc into the central section IIIc. If desired, the step ofcontacting vapors with spray in section 110 can be dispensed with,whereby a lower pressure drop across the chamber 237a is achieved andhigher vacuum is achieved. However, in the latter event, completesettling of entrainment from vapors in section H0 is not achieved,although a substantial proportion of the said entrainment is settled byvirtue of the residence time of vapors in section IIc. Vapors fromsection IIc are passed through baflle section 241 transversely closingchamber 237a and which can be similar in design to bathe section 162 ofchamber 157, and contacted in section IIIc with a spray of atomizedliquid droplets maintained at a temperature sufliciently below that ofvapors contacted therewith so as to effect substantially complete vaporcondensation. When dispensing with the use of a spray in section 110,condensate thus formed in section IIIc contains small proportions offeed particles entrained in vapors entering section IIIc. However, thesmall proportion of unvaporized charge particles present can generallybe justified in view of the lower pressure drop achieved across thedistillation chamber 237a and the higher vacuum resulting therefrom toprovide an improved yield of gas oil'and a correspondingly lowered yieldof residuum.

Operation in sections 1's and II'c is the same as that respectively insections Ia and He and is not specifically illustrated.

Vacuum is applied to distillation chamber 237a by means of steam jets242, connecting with the interior of section IIIc via line 243 andinternal guard chamber 244, the latter being similar in design to guardchamber 216 of distillation chamber 198. Dam means 246, in combinationwith spray nozzle assembly in section IIIc (also illustrated withreference to Figure 7) provides for isolation of condensate fractions insection IIIc, recovered from vapors from sections IIc and 11's.

Residuum product is withdrawn from section Ic of chamber 237a via line247 and can be withdrawn from the system via line 248, or recycled vialine 249 with fresh feed to distillation chamber 237a. Residuum fromsection Ic of chamber 237a is withdrawn via line 251 and can bewithdrawn from the system via line 252, or recycled in part, if desired,via line 253 and 232 to distillation chamber 237a. Liquid product fromsection IIc is withdrawn via line 254, and can be withdrawn from thesystem via line 256, recycled in part as liquid spray in section IIc,when desired, via line 237b, cooler 258, and line 259. Liquid product iswithdrawn from section IIc of chamber 237a via line 261 and can bewithdrawn from the system via line 262, and, when desired, can be passedin part via line 263, cooler 264 and line 266 to spray nozzle assembly2410. Liquid product from lines 254 and 261 can also be each recycled todistillation chamber 237a together with fresh feed, via lines 255 and232, and preheater 233a, these latter recycling steps being particularlyadvantageous when no liquid spray is employed in sections I10 and IIc.

Recycle of residuum from a vacuum distillation system with fresh feedthereto, in preferred forms, is described and claimed in the copendingapplications of William E. Barr and Charley H. Owen, Serial No. 351,017,filed April 24, 1953, now U.S. Patent No. 2,799,628, and Golden A.Moyer, Serial No. 316,411, filed October 23, 1952, now US. Patent No.2,774,723.

By means of the second stage vacuum distillation of my invention, suchas specifically illustrated, the softening point of the first stageresiduum product can be increased by about 50 to 350 F., and the overallyield of gas distillate is correspondingly increased, thereby providingfor lowered yields of residual pitch product, although of betterquality, and higher yields of gas oil.

As illustrated with reference to Figure 11D, residuum product of thesecond stage vacuum distillation, above discussed and illustrated, isfurther processed in a series of steps comprising visbreaking, recyclecracking, and final vacuum reduction, to provide a final high softeningpoint pitch product, and for recycle and reaction, substantially toextinction of gas oil fractions formed, to produce hydrocarbons boilingin the gasoline range as a chief light hydrocarbon product. Thus,residuum from lines 247 and/ or 251, together with, if desired, gas oildistillate from lines 261 and/or 254, although the last said gas oilstreams are generally withdrawn from the system for other utilization,are passed via line 266a, to visbreaking Selas furnace 267, wherein itis heated to a temperature generally of about 750 to 850 F., so as toeffect mild cracking of same. It is generally advantageous to pass astream from line 266a via separator 268, to furnace 267, whereby anyrelatively light fractions can be withdrawn overhead and utilized asdescribed hereinafter. Effluent from visbreaking furnace 267 is quenchedat points 268a and 269 with gas oil from line 271. Steam from line 272is also added at point 269 for control of final quench temperature.Resulting quenched furnace efiiuent at a tem perature such as from 710to 750 F. is passed into vacuum flash chamber 27 3, maintained underabout 1.0 to 10 mm. Hg from which residual product is withdrawn via line274. Vapors from vacuum flash chamber 273 are withdrawn via overheadline 276 and passed to vacuum bubble tower 277, the latter under about1.0 to 10 mm. Hg. Gas oil bottoms product is withdrawn from tower 277via line 278 and is passed in part into line 271 and is withdrawn inremaining part as product via line 279. Overhead product withdrawn fromvacuum bubble tower 277 comprises gasoline in line 281 and gas in line282, separated in separator chamber 283. Residuum in line 274 if passedto a recycle cracking operation in which all gas oil product fromcracking is recycled to the cracking step so that the only products aregas, gasoline, and residuum. Thus, residuum in line 274 is charged tobubble tower 284, operated under vacuum of about 10 to mm. Hg to whichis also charged an aromatic gas oil from line 286, preferably a sulfurdioxide extract oil together with vapors from flash drum 287, describedhereinafter, via line 288. Fractionation in bubble tower 284 providesgas as an overhead product, withdrawn via line 289 and a sidestream ofgasoline withdrawn via line 291, and, a bottom gas oil stream which ischarged to furnace 292, via lines 293 and 294. More severe crackingconditions are maintained in furnace 292 than were maintained in furnace267, e.g., a cracking temperature within the range of 900 to 1100 F.under about atmospheric pressure to 50 p.s.i.g. Water is injected intothe feed to furnace 292 via line 290. Furnace effluent is withdrawn via297 and charged to flash drum 287. Residuum is withdrawn from flash drum287 via line 298 and is charged to surge tank 299. Combined withresiduum from chamber 287 in line 298 is residuum from other refineryoperations, in line 301, recycled pitch from vacuum flash distillationtower 302 in line 303, and superheated steam from line 304. Vacuum isapplied to surge drum 299 via vacuum jets not specifically shown throughline 306 to remove the more volatile components of the feed through line306. Residuum is withdrawn from surge tank 29.9 and passed to furnace307, wherein it is heated to a temperature in a range suitable forvacuum reduction described hereinafter such as about 600-900 F.,preferably such that little or no cracking is effected during theheating. The heated residuum from furnace 307, via line 300 is flashvaporized in vacuum distillation chamber 302, the latter maintainedunder high vacuum such as in the range of 0.10 to 10 mm. Hg, applied byvacuum jets via line 307a. In chamber 302, lighter hydrocarbon fractionsare condensed from the flashed vapors and recovered as products vialines 308 and 309, any uncondensed vapors being removed via the jets.Residual pitch product is withdrawn from distillation chamber 302 vialines 311 and 312, and in part, when desired, via line 303 for passagetogether with steam and the above-described residuum fractions in line298 for further processing in vacuum surge tank 299.

The above-described embodiment, with reference to the combined processsteps of Figures 11A and/or 11B, 11C and 11D, provides a residual pitchproduct of high softening point, for example in the range of 2001 to 450F., and for recycle to extinction of a major proportion of the gas oilfractions recovered during the visbreaking, cracking and vacuumreduction steps, thereby providing for gas and

11. IN A VACUUM DISTILLATION PROCESS WHEREIN MATERIAL IS PARTIALLY FLASHVAPORIZED IN A FIRST ZONE AT SUBATMOSPHERIC PRESSURE, THE IMPROVEMENTWHICH COMPRISES SEPARATING AN UNVAPORIZED PORTION OF SAID MATERIAL FROMSAID VAPORS, FLOWING AN UNVAPORIZED PORTION OF SAID MATERIAL OUT TOCONTACT AND SEPARATED FROM SAID VAPORS TO A SECOND ZONE IN OPEN VAPORCOMMUNICATION WITH SAID FIRST ZONE AND FLASH REDISTILLING SAME AT APRESSURE SUBSTANTIALLY LOWER THAN SAID SUBATMOSPHERIC PRESSURE, SO THATA SECOND FLASH DISTILLATION IS OBTAINED IN THE SAME VACUUM DISTILLATIONSYSTEM, UTILIZING PRESSURE REDUCING MEANS EMPLOYED IN MAINTAINING SAIDSUBATMOSPHERIC PRESSURE, AS THE SOLE SOURCE OF VACUUM FOR SAID PARTIALVAPORIZATION AND SAID SECOND FLASH REDISTILLING.
 29. IN THE VACUUMDISTILLATION OF A HEAVY OIL THE IMPROVEMENT COMPRISING INTRODUCINGLIQUID CHARGE STOCK INTO A DISTILLATION ZONE, UNDER FLASH CONDITIONSPROVIDING FOR VAPORIZATION OF A PORTION OF SAID CHARGE TO FORM VAPORSCONTAINING ENTRAINED LIQUID DROPLETS, IN A DIRECTION OPPOSITE TO THEDIRECTION OF VAPOR FLOW THEREIN AND AGAINST A LIQUID COALESCING SURFACE,UNDER CONDITIONS CAUSING VAPORS EMITTED TOWARD SAID SURFACE TO SUDDENLYCHANGE THEIR DIRECTION OF FLOW SUBSEQUENT TO CONTACTING SAID SURFACE,WHEREBY SEPARATIONS OF UNVAPORIZED AND VAPORIZED PORTIONS OF CHARGE ISFACILITATED AND ENTRAINMENT OF LIQUID IN THE VAPOR FORM IS MAINTAINED BYCOALESCING OF UNVAPORIZED LIQUID DROPLETS ON SAID COALESCING SURFACE,AND DRAINING COALESCING LIQUID FROM SAID SURFACE AND COLLECTING LIQUIDSO DRAINED BELOW SAID COALESCING SURFACE.